This board holds the SEQ's illuminated buttons, which are driven from a shift register matrix. The ENC-PLATE board stacks on top.
A shift register chain of 3 DIN 74HC165 and 2 DOUT 74HC595 chips are used. Two of the DINs scan the encoders and one scans the button columns. The DOUT parts are connected into a matrix. Note that both the high and low sides have driver transistors (PNP and NPN, respectively). This means that the anode side of the matrix will operate with inverted behaviour (pin high = LED off). Actually the low (cathode) side is also “inverted,” as we turn the transistor “on” to sink the current by toggling the 595 pin high.
There are special instructions for connecting the parts which are covered below.
Please find the current BOM on http://midiphy.com. The table below is depreciated and will not be updated.
|16||47R 5%||THT||RJ1-8||see instructions|
|10||100-220R 5%||THT or 1206||SJ1-8, RJ9||see instructions|
|8||10k 5%||1206||R18-25||near NPN transistors|
|3||9*10k||SIP10||RN1-3||bussed network, not 5 pairs of resistors|
|0||do not fit||C6|
|24||BAT54||SOT-23||512-BAT54||BAT 54 SMD|
|16||RGB flat||superflux||ELV: 68-10 94 64||see instructions|
|8||various||3mm||insert into switches|
|3||74HC165||SOIC16||IC1, IC3, IC5||595-SN74HC165DR|
|8||MEC/APEM||3FTH9||SW17-24||642-3FTH9||TASTER 3FTH9||705276 - 62|
note that two sets are required per SEQv4+ build!
v1.0: first release.
The C3 cathode row is missing a PCB trace. Join the two legs of SW19 as shown in pink, preferably on the bottom of the PCB. The LED cathode leg could simply be bent across to the switch pin.
Ghosting. As seems common with these kinds of matrices, there is some unwanted lighting of LEDs. This is most apparent when trying to light up the bottom row of MEC switch LEDs, as the resistive path to the Superflux LED is lower and thus glows unintentionally. This can be overcome somewhat by stacking BAT54 Schottky diodes on top of the BC818 transistors. Later revisions will have more elegant mounting.
Take your time as some of these parts require some patience.
High-brightness LEDs are often expensive or don't have viable mounting options. To get around this, we will use flat-top superflux/piranha RGB LEDs and bend the legs over to make a pseudo SMT part :). There are at least two different LED pinouts, so make sure you know how yours function.
The LEDs are available in RGB, but the official MIDIbox SEQ software only supports two of these colours. (if wanted, you could attach 0.1“ headers to the PCB and drive the LEDs with custom hardware.) So we need to select what LEDs are in the matrix using the resistor jumpers (RJ). Find RJ1-8 spanning across the middle of the board. Pins A(1-8) and B(1-8) represent the 8 anode busses and pins 1, 2 and 3 represent the pins of the LEDs in the row.
RJ9 connects to the Beat LED and so 100-220R resistors should be used here.
Continue on with the header pins. J5 should be connected to the Beat LED PCB; this needs some more thought. Header J14 can be used as a +5V supply. 1*10 Headers J1-3 can be installed, but best in conjunction with the ENC-PLATE PCB to ensure correct alignment.
Here is a good point to test out the BLM function. Some MB_NG app? With the Plate PCB to test out the DIN side?
Notice that the switches have not yet been soldered in. It should be alright to put in the MEC switches, as long as the LEDs have been inserted first! Like the Jog module, the switches must be installed with the LEDs polarised correctly. The clearance with the Plate PCB is tight, so keep them straight.
Note the LED polarisation:
Very important: the Matias switches must go in through the completed Plate PCB! If they are put in before the Plate PCB, the Plate PCB won't fit and there will be no way to mount the encoders!
Once the Matias switches are in, this should basically be the final step of le MEC.
Currently the design is © 2017 antilog devices with all rights reserved; all documentation is CC BY-NC-SA 3.0.